CVE-2026-82755
ash_authentication_oauth2_server serves tenant-specific OAuth metadata as publicly cacheable without Vary, enabling cross-tenant confusion
No known exploitation. EPSS puts it in the 49th percentile. No fix published yet.
What to do
No fixed build or workaround is published yet. Limit exposure and watch for a patch.
What it is
From the CVE record
Use of Cache Containing Sensitive Information vulnerability in ash-project ash_authentication_oauth2_server allows a shared HTTP cache to serve one tenant's OAuth discovery metadata to another tenant's clients. The RFC 8414 and RFC 9728 metadata endpoints in AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter return tenant-specific values (issuer, authorization_endpoint, token_endpoint, jwks_uri) when a tenant is set, but sent them with Cache-Control: public, max-age=3600 and no Vary. When the tenant is derived from something other than the URL (a header or the Host) and a shared cache sits in front, the cache key is the URL alone, so a stored response for one tenant is served to another for up to an hour. Affected clients may then send authorization codes and secrets to the wrong tenant's token endpoint and validate tokens against the wrong keys. This issue affects ash_authentication_oauth2_server: from 0.1.3 before 0.3.1.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
0.7% chance of exploitation activity in the next 30 days, which ranks it in the 49th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
4 events over 1 day, from the signal feeds we watch.
- Record updated
- Publishedweakness classified, record updated
Affected products
Technical detail
Weaknesses
Sources
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